In metal and ceramic creep test laboratories, for example, extensive testing of materials is carried on for long periods of time during which the test equipment is unattended. The equipment in these laboratories include a number of flexible hoses used for cooling water and hydraulic fluids which operate under pressure. Since the laboratories are often unattended, especially when operated around the clock, large quantities of these liquids may be spilled on the floors and work surfaces before being discovered.
These liquid spills have a number of consequences. With an oil spill, it becomes very important to prevent large quantities from entering the building drain system due to prohibitions on oils in waste water and the subsequent fines. If a water hose fails, the loss of cooling water to a test machine can cause considerable equipment damage. In either case, cleanup after extended flooding is costly and time consuming.
A search for commercially available liquid spill detectors which could be electrically connected to a remote alarm system, revealed that the available detectors work only to detect electrically conductive liquids and thus would not work in a situation where both water and oil spills are to be detected. The available detectors function to detect an electrically conductive liquid through a change in the resistance between spaced electrode arrays which are located in an area to be contacted by these liquids. These devices are insensitive to nonconductive liquid spills, such as oil spills, and further could be made insensitive to water spills, for example, if first coated with an oil spill. Therefore, it will be appreciated that there is a need for a liquid spill detection device which is sensitive to both conductive and nonconductive liquid spills.